Stereo Bleed After Exporting

Hello,

I have scoured the internet but I have yet to find a solution. It is driving me crazy. I am using Audacity 2.2.1 on Windows 10.

I create a rhythm track and pan it 100% left. When I play the track in Audacity as a project I see nothing in the right channel up to -120 dB.

I export this track as a WAV. When I open this WAV file in audacity, I see signal on the right side at -72 dB.

Why is this happening and how do I stop it?

Screen Print of Audacity Project During Playback:
AudacityProject.jpg
Screen Print of Audacity WAV Import During Playback:
AudacityWAVImport.jpg
Thanks in advance!

All the best,
DAve

Audacity adds a dither signal to WAV exports to keep the bit depth conversions from lining up and becoming audible.

Audacity edits internally in 32-floating. When you export, it has to convert to 16-bit, a lower grade, common format. To prevent occasional digitizing errors it adds shaped noise.

Does your destination support 32-bit floating? If so, you can export in that format and turn dithering off, although I think it goes off automatically in that case.

Koz

Thank you so much!

It was happening in all formats: WAV 16, WAV 32, MP3 (stereo and joint stereo), and AIFF.

I went to Edit > Preferences > Quality > High Quality Conversion and changed Dither to None and that resolved the issue.

Really appreciate your help

Sincerely,
Dave

changed Dither to None and that resolved the issue.

It solved that particular issue, yes.

32-Floating is the only one that doesn’t need it. I thought it went off by itself, but if it doesn’t, you can turn that one off manually.
Screen Shot 2018-02-18 at 21.20.44.png
Koz

Unfortunately, while I can no longer see any audio signal in the right channel of the export in audacity, I can still hear it during playback on all the devices I have tested it on (iPhone, iPad, PC, and Microsoft Surface). It is very faint, but it is still there.

it

Let’s do “it” for a minute. In that thread you complained about two different things: crosstalk of your drum or rhythm track and the fffffff sound of the dither signal.

Which is it?

There is one way to get crosstalk in Windows. Windows can filter your performance through a special effects program. I got a machine stuck in “Cathedral Effects” once and it would not pass playback testing. One of the failures was crosstalk.

Does it work the other direction? If you put the signal on the right, does it cross to the left?

How did you determine that the crosstalk was 120dB and then 72dB?

Koz

Analyze → Sample Data Export Will create a text file with the sample values. (It may not export the full file… By default it saves the first 100,000 samples.)

Without dither there are zeros (“dead-digital silence”) in the right channel:

sample-data10.txt 2 channels (stereo)
Left channel then Right channel on same line.
Sample Rate: 48000 Hz. Sample values on linear scale.
Length processed: 100000 samples 2.08333 seconds.

-0.02878 0.00000
-0.02896 0.00000
-0.02942 0.00000
-0.02997 0.00000
-0.03012 0.00000
-0.03003 0.00000
-0.03012 0.00000
-0.03027 0.00000
-0.03043 0.00000
-0.03073 0.00000…

With dither the right channel is no longer silent:

sample-data11.txt 2 channels (stereo)
Left channel then Right channel on same line.
Sample Rate: 44100 Hz. Sample values on linear scale.
Length processed: 100000 samples 2.26757 seconds.

0.00003 0.00003
-0.00009 -0.00006
0.00012 0.00003
-0.00012 0.00000
0.00012 0.00000
-0.00009 0.00003
0.00006 -0.00006
-0.00006 0.00003
0.00006 0.00000
-0.00003 0.00000
0.00003 0.00000
-0.00006 -0.00003…



I can still hear it during playback on all the devices

I is really crosstalk (the signal from the left channel) or is it dither (noise)?

I doubt you’re hearing it under any “normal” listening situation where you are listening to both channels, and you certainly aren’t hearing it with speakers (where the left & right sounds are mixing acoustically in the air).

…I remember the days of analog vinyl when 20dB of separation was good! :slight_smile:

My apologies for the confusion. The “it” is the crosstalk, not the fffff. I have been trying to find and eliminate the source of the crosstalk and I assumed that was what I was seeing at -72 dB in Audacity after I exported the track and reimported.

To see the signal at -72 dB and less on the right channel in Audacity, I went to Edit > Preferences > Interface and changed Meter dB Range to “-120 (approximate limit of human hearing)”. I am no longer certain that what I was seeing was actually the crosstalk.

Yes, the crosstalk also happens if I swap the signal to the right, it crosses to the left.

How does one determine if there are special effects programs running on the machine? Would it be under the Playback or Recording devices?

A little background… I’m trying to create backing tracks for live band situations, where the click and cues are panned hard left and samples are panned hard right. The track will then be split and the click sent to the band and the samples to the house. But because of the crosstalk issue, I am able to hear the click in the house.

Thanks again!

All the best
Dave

A little background… I’m trying to create backing tracks for live band situations, where the click and cues are panned hard left and samples are panned hard right. The track will then be split and the click sent to the band and the samples to the house. But because of the crosstalk issue, I am able to hear the click in the house.

Could it be your mixer, or somewhere else in the analog chain? Crosstalk in the analog electronics isn’t surprising at all, especially if you’re relying on the mixer’s pan-pots. You may need a separate little mixer for monitoring.

But… If it’s really 70dB down the audience is never going to hear it when the band is playing and they probably won’t hear it over the background/audience noise even if the band isn’t playing.

The track will then be split and the click sent to the band and the samples to the house.

Perfectly rational, but how are you getting it there? What happens between the computer and the house? You’re flirting with the crosstalk specifications in the digital interface and (as above) the mixer. You’re also assuming all the cables are perfect.

Unless you’re messing about with higher-end mixing desks, you may have reached the end of what it can do. The purpose of home mixers is to record grandma’s zither solo where nobody’s going to notice if the channels aren’t 70dB apart. You are designing live production special effects.

To specifically answer you, I don’t remember where the effect was. I’m trying to play that event back in my head.


Ummmm.

Right-Click the speaker lower right > Playback > Device (pick yours) > Properties > Enhancements.

Koz

Thanks for the replies!

I can hear it through my iPhone headphones when I play the file from google Drive for example, taking the splitter cable and mixer completely out of the equation.

The crazy thing is that it does not show up in Audacity all the way down to -120 dB when I import the export, but when I play it outside of Audacity the crosstalk is clearly there, and much louder than -72 dB. I’ve tried a plethora of different playback devices, head phones, and file types, and it is still there.

It definitely cannot be heard over the band, but I can hear the count ins before songs during practice through the PA speakers even with my ear plugs in.

Truly appreciate all the help.

All the best,
Dave

This effect is why Broadcast and Studio connections are all made with electrically balanced cables and XLR connections.




… and not home style RCAs.

Koz